[Amps] Command HF2500 conversion to 6m

Ed Stallman n5blz at peoplepc.com
Tue Dec 26 21:12:15 EST 2006


Hello Amper's

 Here's what I've got to work with, a lightning struck Command HF2500. The
no good parts are... Control Board, HV power Supply, The Zero crossing
solid state relays and the QSK board. The HV transformer I have not tested !

Here are my plans with questions. I am going to use the chassis, tube
socket's, blower and filament transformer to make a 6m amp only! I have 2
new 3cpx800a7, a WD7S full wave HV board and a Peter Dahl HV transformer,
2500 VAC @ 1.5 amp CCS, This should give me 3500 VDC ?

My list of questions

!  Am I correct, 2500 VAC @ 1.5 amp CCS to a WD7S Full Wave bridge, 3500 VDC ?
2  Will the 3500 VDC work with the 3cpx800a7 ?
3  The filament transformer at the tube socket reads 15.6 volts, I think
this should be 13.6? will the voltage drop with the tube's in place?
4  Will I be able to use the filament choke's that are there now for 6 meters?
5  How about the original HV choke, from what I've read , I need 40 turns
#22 on a 3/4 inch ... what do you think?
6  The original Load capacitor, I'm not sure what the value is? I think I
need around 250/ 300 PF ?
7  I know for the Tune Capacitor, I will need a Vacuum variable 3 to 30 PF
but I have seen on the 8877 and gs35 were they mesh two plates together for
C1... Is this possible with 2 x 3cpx800a7 ?
8  I have found lots of information on the Internet about  6 meter PA's
using 8877 or gs35 and a single tube amp would be easier to build but I'm
using what I have on hand.
Does anyone have the drawing of the Command VHF2000 6m amp, RF deck only ?

I hope everyone is having a great Holiday Season
Thanks Ed N5BLZ



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